As a golf ball flies, from having been hit with a golf club, and discounting any spin which may have been imparted to the ball by the angular impact direction of the golf club on the golf ball, its forward progress through the air is impeded by eddy currents and the consequent vacuum which is created rearward of the flying ball. To the extent that the air passing around the surface of the flying golf ball is broken up from laminar flow, the eddy currents, and thus this vacuum, is reduced. Thus, golf balls have dimples on their surface to break up the otherwise laminar flow of air over the surface of the golf ball. It is known that increasing the number of dimples increases the distance that a golf ball will fly when hit with the same power. The speed of the air around a flying dimpled golf ball is lower than the air speed would have been had the golf ball had a smooth surface with no dimples. This causes the eddy currents rearward of the ball to be in a narrower area and this reduces the drag on the flying golf ball.
To date, the effort has been to place as many dimples on the surface of the golf ball as possible in a generally symmetrical pattern. To accomplish this, dimples of different sizes have been placed on the surface of the golf ball. Because the dimple patterns are made up of different sized dimples, the performance of the golf balls has been non-uniform because the spin imparted to the golf balls on impact by the golf club has a different effect depending on the particular placement of the different sized dimples. The frictional resistance and the amount of drag are dependent on the way the ball is rotating and therefore uniformity of performance is not achieved.
In the prior art, placing the dimples in a symmetrical pattern has been accomplished by dividing up the surface of the golf ball sphere geometrically symmetrically. The dimples were then placed within these symmetrical subdivisions. The so-called "dimple pattern, which is the criteria for dimple placement, was then applied mechanically by a manufacturing procedure. The dimple pattern is not the dimples themselves, but is the pattern at which the dimples will be placed. The most popular and typical example of a dimple pattern is shown in FIGS. 1 and 2.
In FIG. 1a, there is shown a side view of a golf ball with the three equators marked thereon. FIG. 1b is a polar view of this same golf ball. For convenience, the areas of dimple emplacement in FIG. 1 is referred to as a "spherical triangle pattern". The succession of eight spherical triangles 21 are defined by the intersecting three equators 11, 12 and 13 of the sphere. The poles 31 and 32 are arbitrarily two opposite points of intersection of two equators. The dimples within any one of the spherical triangles 21 are formed in rows which are parallel to the sides of the triangles 21.
Since the rows of dimples in such a conventional construction are parallel to the sides of the triangles, these rows of dimples form a fixed sinusoidal path for the air passing over the golf ball during flight. Such a path does not reduce the adverse effect of the aerodynamic passage of the air. These problems are especially described in U.S. Pat. No. 4,141,559, and British patents 1,402,271 and 1,401,730. U.S. Pat. Nos. 4,848,766 and 4,765,626 disclosed a new dimple pattern as a means of overcoming the detrimental behavior of the conventional, spherical triangular dimple arrangement. According to the U.S. Pat. No. 4,848,766, the conventional spherical triangular pattern is used, but two different sized dimples were formed within this spherical triangle pattern. This dimple pattern disclosed in this reference had a detriment in that the ratio of small to large dimples was fixed. This forced the designer into using a fixed number of dimples of a particular size, or at least a fixed ratio of small to large dimples as this may yield optimum performance. This disclosure did however remedy the situation of the dimples always being parallel to the equators.
In addition, the disclosure of U.S. Pat. No. 4,765,626 provided for additional small triangles to be formed at the several intersections of the three equators. Dimples were arranged in both the large spherical triangles and in the small triangles. However, this did not sufficiently remedy the situation because the apices of the large and the small triangles were coincident.